This invention relates to an apron-conveyor connection for loading and conveying machines, and is an improvement over the connection concept disclosed in U.S. Pat. No. 4,011,936 issued to Henry C. Hall on Mar. 15, 1977 and entitled "Conveyor Positioning Structure For Loading And Conveying Machines".
Such machines utilize a front end gathering implement to sweep rock, sand, ore or other lose material onto a self-contained conveyor for transport to a discharge location, usually disposed at the rear of the machine. An apron is disposed at the forward conveyor end, has a front end edge adapted to move forwardly along the ground with the machine and a rear end portion over which the material moves onto the conveyor. The gathering implement is normally mounted to the front portion of the machine frame, extends substantially ahead of the apron and is adapted to force material up the inclined apron.
Vehicle transport means, such as crawler treads, support the machine on the ground and may be positioned substantially behind the apron and front frame portion to move the center of gravity of the entire device rearwardly in view of the substantial weight forces at the front.
The loading and conveying machines under consideration here can be utilized in tunneling operations, although it is contemplated that they may find more extensive use above ground. In any event, they are often subject to variations in level of terrain, both during actual loading and also during transport from place to place.
It has been found that the gap or clearance space between the rear apron edge and the conveyor should be as narrow as possible. If material rolls backwardly down the inclined conveyor, as sometimes happens, it may tend to enter a gap which is too wide and thereby jam the mechanism.
In the aforementioned patent, the gap width was narrowed by pivotally mounting the front end of the conveyor to the apron itself. The pivotal mounting defined a single axis which was common to both the center of rotation of the conveyor on its front sprockets, as well as to the mounting shaft connecting the apron and conveyor.
When the apron and conveyor are pivotally connected, and as the apron is raised or lowered, the apron carries the conveyor front end with it. As part of this movement, the gap between the rear apron edge and conveyor varies in width within a given range. The smaller the gap and its variance in width, the less chance there is for jamming and other problems created as the loaded material passes over the rear apron edge onto the conveyor.
It is a task of the present invention to reduce the gap and its range of width even further than that provided by the structure of the aforementioned patent, without causing the major machine parts to collide with one another.
In accordance with one aspect of the invention, the axis of apron-conveyor pivotal mount is removed from the center of rotation of the front end of the conveyor and spaced rearwardly and downwardly therefrom.
In accordance with another aspect of the invention, the distance between the rear apron edge and the axis of apron-conveyor pivotal mount is greater than the distance between the said edge and the center of rotation of the front end of the conveyor.
In accordance with yet another aspect of the invention, the axis of apron-conveyor pivotal mount is disposed in a transverse vertical plane which is positioned between the rear apron edge and the center of rotation of the front end return portion of the conveyor.